1. Technical Field
The present invention relates generally to a linear vibration motor and, more particularly, to a linear vibration motor, in which a bearing is provided on an extension part of a spring coupling a motion part and a stationary part of the motor with each other, or a ball is provided on a protruding part of a yoke, thus minimizing friction and abrasion between adjacent parts when the motor is in operation, minimizing noise caused by the friction and abrasion thereof, and vibrating in a horizontal direction.
2. Description of the Related Art
The most important function of a receiving device, the representative example of which is a mobile phone, is a receiving function informing the receipt of a signal. This function is performed through the production of the sound of a bell or vibration. The vibration especially becomes an essential element of the mobile phone so as to prevent people from being annoyed or to allow the recognition of the receipt of a signal at a position where it is difficult to recognize the sound of the bell.
A vibration motor is a means for generating vibration and is constructed so that its axis is eccentric or the center of gravity leans to one side and thereby the motor generates vibration when the motor rotates. Such a vibration motor is problematic in that a brush passes through a gap between segments when the motor rotates, so that mechanical friction and electric sparks are generated, and the lifespan of the motor is short. Further, when voltage is applied to the motor, it takes a long time to reach a target vibration strength because of rotating inertia, so that it is difficult to realize vibration suitable for a touch screen phone.
In order to overcome the drawbacks of the vibration motor, a linear vibration motor has been developed. In the linear vibration motor, a vibrator mounted to a plate spring is vibrated by electromagnetic force between a magnet and a coil, so that mechanical friction does not occur and the miniaturization of the motor is possible. Therefore, a variety of types of linear vibration motors are being currently developed. Here, the electromagnetic force is generated by interaction between a magnet located in a motion part and DC or AC having a predetermined frequency of a coil located in a stator.
As shown in FIG. 11, a conventional linear vibration motor 10 includes a vibrator 12, a coil 13, a magnet 14, a plate 15, and a yoke 16 in a casing 11. The vibrator 12 is vibrated up and down by electromagnetic force between the coil 13 and the magnet 14.
The linear vibration motor is generally located at the corner of a mobile phone, thus generating vibration on an LCD screen in a vertical direction. The linear vibration motor designed to vibrate in the vertical direction may generate vibration when the vibrator 12 ensures vertical displacement and moves. However, the increase in the thickness necessary to increase the vibration strength is limited because of the restriction of a mounting space in the mobile phone.
In order to overcome the drawback of the conventional linear vibration motor 100, a method of horizontally moving a mass part in the linear vibration motor has been proposed.
However, the linear vibration motor vibrating horizontally is problematic in that parts are apt to wear because of friction between the vibrator 12 and adjacent parts. Therefore, the development of a linear vibration motor which is capable of reducing the abrasion of parts while vibrating horizontally is pressing.